Thrombophilia / DVT / HITUrgent

Swollen, painful left leg for 3 days after surgery; or platelets fallen >50% on day 5–10 of heparin with a new clot

• Chest pain, breathlessness, syncope (PE)
• Cold, blue, painful limb (phlegmasia)
• Skin necrosis at injection sites (HIT)
• Bleeding on anticoagulation

• Cellulitis
• Ruptured Baker cyst
• Muscle tear or haematoma
• Lymphoedema, venous insufficiency
• Other causes of low platelets on heparin (sepsis, DIC, drugs)

• Admit: Phlegmasia, massive iliofemoral DVT, symptomatic PE, HIT, high bleeding risk, severe renal failure, or unsafe at home
• ICU: High-risk PE, limb-threatening ischaemia

• Isolated distal (calf) DVT without severe symptoms: repeat ultrasound at 1–2 weeks is an alternative to anticoagulation.
• Most DVT and low-risk PE are treated at home with a DOAC.
• HIT is prothrombotic, not a bleeding disorder — the platelet fall is modest (rarely <20×10⁹/L).
• Unprovoked VTE: limited cancer screening only — extensive CT searching does not improve outcomes.

• Start or continue warfarin alone in acute HIT — venous limb gangrene
• Give LMWH or heparin flushes when HIT is suspected
• Test for thrombophilia during the acute clot or on anticoagulants
• Transfuse platelets in HIT without bleeding

• Not age-adjusting the D-dimer
• Missing HIT because platelets are "only" 90×10⁹/L
• Starting warfarin during acute HIT
• Thrombophilia testing on anticoagulants

Home with a DOAC for most DVT; ward for phlegmasia, PE, HIT or high bleeding risk; review at 3 months for duration.